Poly(butylene 2,6-naphthalate) (PBN) is a crystallizable linear polyester containing a rigid naphthalene unit and flexible methylene spacer in the chemical repeat unit. Polymeric materials made of PBN exhibit excellent anti-abrasion and low friction properties, superior chemical resistance, and outstanding gas barrier characteristics. Many of the properties rely on the presence of crystals and the formation of a semicrystalline morphology. To develop specific crystal structures and morphologies during cooling the melt, precise information about the melt-crystallization process is required. This review article summarizes the current knowledge about the temperature-controlled crystal polymorphism of PBN. At rather low supercooling of the melt, with decreasing crystallization temperature, β’- and α-crystals grow directly from the melt and organize in largely different spherulitic superstructures. Formation of α-crystals at high supercooling may also proceed via intermediate formation of a transient monotropic liquid crystalline structure, then yielding a non-spherulitic semicrystalline morphology. Crystallization of PBN is rather fast since its suppression requires cooling the melt at a rate higher than 6000 K·s⁻¹. For this reason, investigation of the two-step crystallization process at low temperatures requires application of sophisticated experimental tools. These include temperature-resolved X-ray scattering techniques using fast detectors and synchrotron-based X-rays and fast scanning chip calorimetry. Fast scanning chip calorimetry allows freezing the transient liquid-crystalline structure before its conversion into α-crystals, by fast cooling to below its glass transition temperature. Subsequent analysis using polarized-light optical microscopy reveals its texture and X-ray scattering confirms the smectic arrangement of the mesogens. The combination of a large variety of experimental techniques allows obtaining a complete picture about crystallization of PBN in the entire range of melt-supercoolings down to the glass transition, including quantitative data about the crystallization kinetics, semicrystalline morphologies at the micrometer length scale, as well as nanoscale X-ray structure information.

聚（2,6-萘二甲酸丁二酯）（PBN）是可结晶的线性聚酯，在化学重复单元中包含一个刚性的萘单元和一个柔性的亚甲基间隔基。由PBN制成的聚合物材料具有出色的抗磨性和低摩擦性能，优异的耐化学性以及出色的阻气性。许多性质取决于晶体的存在和半结晶形态的形成。为了在冷却熔体期间形成特定的晶体结构和形态，需要有关熔体结晶过程的精确信息。这篇综述文章总结了有关PBN的温度控制晶体多态性的最新知识。在较低的熔体过冷度下，随着结晶温度的降低，β'和α晶体直接从熔体中生长出来，并组织成截然不同的球状超结构。在高过冷度下也可能会形成α晶体通过中间形成瞬态单向液晶结构，然后产生非球形半结晶形态。PBN的结晶相当快，因为​​其抑制作用需要以高于6000 K·s ^-1的速率冷却熔体。因此，研究低温下的两步结晶过程需要应用复杂的实验工具。这些包括使用快速检测器和基于同步加速器的X射线以及快速扫描芯片量热法的温度分辨X射线散射技术。快速扫描芯片量热法可通过将其快速冷却至其玻璃化转变温度以下，从而将瞬态液晶结构冻结在转变为α晶体之前。随后使用偏光光学显微镜的分析显示了其质地，X射线散射证实了液晶元的近晶排列。多种实验技术的结合使得您可以获得有关在整个熔融过冷直至玻璃化转变期间PBN结晶的完整图片，